Brush spring assembly



March 29,1949. w. T. TABER 2,465,943

BRUSH SPRING ASSEMBLY FiledJan. 24, 1944 TTzber.

Patented Mar. 29 1949 BRUSH SPRING ASSEMBLY William T. Taber, Bloomfield, N. J., assignor to Bendix Aviation Corporation, Teterboro, N. J.,

a corporation of Delaware Application January 24, 1944, Serial No. 519,581

2 Claims.

This invention relates to spring assemblies commonly employed in generators and similar electrical equipment, for the purpose of urging brushes into engagement with a commutator or slip ring. I It is usual to employ a spiral spring for this purpose. Ordinarily such a spring is anchored at its inner end, and after being tensioned its outer end engages the brush to urge the latter as above indicated.

With the known arrangements certain difficulties have developed which are overcome by the present invention. When a spiral spring of the type commonly used is tensioned, and with its inner end fixed, there is a distortion in the shape 'of the spring which results in an elongation in which is, of course, a factor which it is desir- :able to avoid.

If the spring is unconfined there is danger -of these distorted turns contacting the frame of the electrical apparatus with a resulting shortcircuit. If the spring is confined, the distorted turns will engage the casing and create additional friction.

An object of the invention is the provision of a spring assembly of the type noted in which a spiral spring is mounted within a casing with its inner end anchored to a member that is adapted to be rotated to partially tension the spring.

Under a condition of partial tensioning, the outer turn of the spring might engage the casing wall, but when the tensioning is complete, as by moving the outer end into brush engaging position, all turns of the spring are substantially free from each other and the outer wall and a condition of symmetry obtains. Thus, the

spring is adapted to function with substantially y no frictional resistance and definite assurance is had that the brush will be properly urged into commutator engaging position at all times.

Various other more detailed objects and advantages of the invention will in part become apparent and in part be hereinafter stated as the description of the invention proceeds.

For a full and more complete understanding of the invention, reference may be had to the assembly made in accordance with the precepts of this invention;

Fig. 2 is an end view mostly in elevation, but partly in section, showing the manner in which the brushes are affected by the spring assembly;

Fig. .3 is a View developing the various elements of the assembly in exploded relation;

Fig. 4 is a detailed section taken about on the plane represented by the line 44 of Fig. 3;

Fig. 5 is a section through the assembly taken. on a plane normal to the shaft on which the springs are mounted; and

Fig. 6 is a diagrammatic showing bringing outthe relative position of the turns of the spring.

Referring now to the drawing wherein like. reference characters denote corresponding parts. and first more particularly to Figs. 1, 2 and 3, a supporting bracket is therein depicted and referred to in its entirety by the reference character B. The bracket B comprises a flange Ill which may be aifiXed to the casing or supporting structure of the particular piece of equipment in which the assembly is being installed.

Thus, the flange 10 might be afiixed to the casing of a generator through the medium of fastening elements which pass through the openings shown at II. If desired, a piece of insulation, such as shown at l2 in Fig. 2, might be interposed between the flange ill and the casing.

Integrally joined to the flange H) is a main frame l3 having a rectangularly shaped opening l4 through which the extremities of the springs to be later described are adapted to pass. This frame I3 may carry end flanges l5 and a downwardly depending front flange B6 to which is secured a bracket member H. A shaft I8 is carried by this bracket member I1 in spaced relation to the remainder of the plate l3 and associated structure, as is clearly brought out in Fig. 3.

It will be noted that shaft I8 is formed at each end with an opening l9. One pair of springs is adapted to be mounted on one end of the shaft. l8 and a similar pair on the other end. In the illustrated embodiment of the invention the assembly is shown as including four springs which. are identified as 26, 2| 22 and 23. The springs 2|] and 2| are assembled as a pair on one end, of shaft l8, and the springs 22 and 23 as a pair on the other end.

Inasmuch as these pairs of springs are substantially duplicates and each spring being similar to every other spring, only one of them is: here described for the purpose of this specification.

and has its inner end bent over into a flange that is received in the kerf 25. Th dou'ter end of the spring is bent into the Li-shaped forma; tion shown at 3!, and this bend, receiyesqa a foot 33 that engages a brush such as depicted at 34. The brush 34 in turn engagesthe'coni' mutator indicated at 35.

A curved casing 01 shield is represented at 36 and. may be carried by a flat wall or disc like member 37 that is formed inte ral with the member 32 and which has a, central opening receiving the shaft [8.

In operation, prior to positioning of the mem- 'ber 32, over the brush, the spring 29 'is first partially tensioned by rotating the inner sle'eye 24;, a required distance. After the desired degree of tension is established, the cotterpin 28 is positioned in aligned openings 2 and 1 9 to maintain this relation.

In this condition the outer turn of the spring 29. will probably engagethe casing" 36. However, when the member 32 is positionedover the brush 34, the, spring is tensioned its outer nd and this rtensioning frees the outer turn of the spring from the casing 36, Thus', when the spring 29 is in effective brush urgingpos ition all turns of the spring are substantially rie'eimm each other and the outer casing.

While only one emlrqodiment of the invention is hereinbefore set forth, it is to be clearly understood that the invention is not to limited to the exact construction illustrated and described,

because various modifications of these details may be provided in putting theinvention into practice within the purview of the appended claim What is claimed is: 1. In a brush holder, th combination of a frame adapted to hold a brush relative' to a commutator and having an exterior projection transverse to the commutator axis, a shaft element including an inner end supported {by said projection and extending along said axis and havin a p n p ni d a nt t i s." oute f e end, a sleeve adapted to be fitted over said shaft element from its free end having a. plurality of outer end apertures adapted for selective register with said opening for holding by the pin, said sleeve having means next inwardly thereal ong from said apertures providing for turning the sleeve relative to said shaft element and a kerf extending from adjacent to said turning means toward the inner end of the sleeve, a member at one side of said projection having a plate-- like portion through which the shaft element extends, said member including a portion of substantially Z-shape, one arm of which is adapted to engage said brush, a spiral spring having an inner end in said kerf and an outer end hooked over an intermediate bend of said Z-shape, a disc surrounding said shaft element, and a spring cover portion carried by said disc closed at one end thereby and open at the other end of the coverportion, saidcoven portion being' operative before the spring; is" operatively loaded to slightly compress 'oiiter turns only of the completely relaxed spring, and said sleeve being operative to load the spring from its inner n'ato reduce tension on said outer turns before the inner. turns tighten on each other for maint. ta ingallfdf-the turns in radially spaced relaac-tuating member 32 of similar shape which has,

tion to each other, said outer turn being in radially spaced relation to said cover portion when operatively related to the brush.

2 In a brush holder, the combination of a frame adapted to hold a brush therein relative to a commutator, a shaft element fixed at its inner end tosaid frame and having a'iree outer end and. including holding means intermediate said ends, afsleeve adapted to be'f tted over said shaft element from its free end and having means adapted for cooperation with said holding means for. selectively positioning the sleeve in fixed relation thereto in any of a plurality of positions of th'e'sleeve about said shaft'element, a member through which said shaft element extends navy ing an arm adapted to engage said brush, aspiral spring fixed at its inner end to saidsleeve-and having n outer end biasing said arm toward said brush, adisc-like member, surrounding said shaft element, and a spring cover portion carried by'saf'id msmam cover portion beingoperative beforethe spring" is operatively' loaded to slightly compress outer turns onlyof the completely relaxed spring, and said sleeve being operative to load the spring from it's'inn-er'endto reducetension on said outer turns "before the inner -turns tightenpn each other for maintaining all of the turnsin radially spaced relatioii to each other," said outertiirn being in ra dially spaced relation" to said cover portion when operatively related to thebr'ushf; WILLIAM T; TABER.

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2,391,421 Klingner Nov. 10, 1952 

